Eccentric groove generating device



March 6, 1956 G. F. CAREY ET AL 2,736,965

ECCENTRIC GROOVE GENERATING DEVICE Filed Jan. 1.9, 1955 ,2 Tlql.

INVE TORs: 5502 4- .c gesr /INK B. AKOFF BY II Mz/AM 1 574/755 United States Patent ECCENTR IC GROOVE GENERATING DEVICE George F. Carey and Frank B. Rakolf, New London, and William F. Saars, Niantic, Conn., assignors to the United States of America as represented by the Secretary of the Navy Application January 19, 1955, Serial No. 482,911

7 Claims. (Cl. 3327) (Granted under Title 35, U. S. Code (1952), see. 266) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

This invention relates to a device for cutting an eccentrio terminating groove in a recording disc and, more particularly, to a device for cutting an eccentric terminating groove in a recording disc beginning at any desired position on the recording disc.

Devices for cutting an eccentric terminating groove in a recording disc are well known in the art. Such grooves may be specifically used in actuating the mechanism of a standard record changer. In the past, a special fixture was necessary for each different diameter disc on which an eccentric terminating groove was to be cut. Thus, it was necessary to provide a separate unit for seven, ten, twelve, and sixteen inch recording discs.

This invention contemplates a single fixture which may be adjusted to cut terminating eccentric grooves on a recording disc beginning at any desired distance from the center and at any azimuth angle relative to the drive pin on a standard recording turntable. Briefly, this is accomplished by the use of a face cam and a cam follower which controls the position of the cutting head.

It is therefore an object of this invention to provide a device for cutting an eccentric terminating groove beginning at any desired distance from the center of a recording disc.

It is a further object of this invention to provide a device for cutting an eccentric terminating groove on a recording disc beginning at any angle relative to the position of the drive pin of a standard recording turntable.

It is a further object of this invention to provide a device for cutting an eccentric terminating groove on a recording disc of any diameter up to a given maximum.

It is a further object of this invention to provide a device for cutting an eccentric terminating groove in a recording disc utilizing a face cam and a cam follower to control the position of the cutting head.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

Fig. l is a plan view of a preferred embodiment of a device employing the principles of this invention, and

Fig. 2 is a cross section of the device shown in Fig. 1 taken across center line AA.

Referring now to the figures, first member 10 has a groove 12 cut in the face thereof to form a face cam. Groove 12 has the configuration of the eccentric terminating groove to be cut in the recording disc.

First member 10 has a hole through the center thereof through which second member 14 is inserted. Second member 14, which engages first member 10 through bushing 28, is rotatable relative to first member 10. Bushing 28 is supported by washer 30 and retaining ring 32. Sec- 2,736,965 Patented Mar. 6, 1956 "ice I 2 0nd member 14 is equipped with handle 16. An indenta tion 68, which is engageable with the center pin of the standard recording turntable, not shown, is provided in second member 14.

Longitudinal third member 34, which comprises an arm parallel to and above the face of first member 10, is slidably engaged with second member 14. Key 62 is provided for allowing only axial movement of third member 34 relative to second member 14.

Third member 34 has a fixed collar 36 attached to one end thereof. Cutting head 42 is slidably engaged with third member 34 on the other side of second member 14 from fixed collar 36. The position of cutting head 42 along third member 34 can be set by means of movable collars 38 and 40 and spring 56. Movable collars 38 and 40 may be secured to third member 34 by means of set screws 44 and 46, respectively.

The depth of cut of cutting stylus 52, which is held by set screw 64 is controlled by the position of advance ball 54. The position of advance ball 54 is dependent on the position of adjustable screw 48.

Inserted in a hole through third member 34 and riding in groove 12 is cam follower 58. To allow for wear of cam follower 58, nut 60 is provided for adjusting the position thereof. 7

First member 10 has a cutaway portion into which is fitted fourth member 18. First'member 10 and fourth member 18 are rotatable with respect to each other, but may be locked together. This lock consists of groove 20, cut into the side of first member 10, hole 22 through fourth member 18, slug 24 inserted in groove 20 and hole 22, and set screw 26 for exerting pressure on slug 24 against the side of first member 10. Indentation 66 is provided in fourth member 18 in cooperative relationship with the drive pin on a standard recording turntable, not shown.

Considering now the operation of the invention, a recording disc of any diameter on which an eccentric groove is to be cut is placed upon a standard turntable provided with a drive pin. At this time, the disc already has been recorded. The eccentric groove generating device is set upon the disc in a position such that indentation 66 engages the drive pin of the turntable and indentation 68 engages the center pin of the turntable.

Advance ball 54 is lowered by means of adjusting screw 48 to a point where cutting needle 52 does not contact the recording disc. With set screw 26 tight so that fourth member 18 is locked with first member 10, second member 14 is held stationary by means of handle 16 and the turntable is rotated, rotating fourth member 18 and first member 10, until cam follower 58 is at its starting point, which occurs at the outer end of the spiral groove 12. Set screw 26 is now loosened, unlocking first member 10 from fourth member 18, and first member 10 is held stationary as the turntable and fourth member 18 are rotated. When the cutting stylus is in the proper azimuth position; that is, pointing in the direction of the end of the last recorded groove on the recording disc, set screw 26 is tightened, locking first member 10 to fourth member 14.

Set screws 44 and 46 on movable collars 38 and 40, respectively, are loosened, and cutting head 42 is moved along third member 34 until cutting stylus 52 is right over the end of the last recorded groove on the recording disc.

Set screw 26 is again loosened, unlocking first member 10 from fourth member 18 and a fine azimuth adjustment is made by turning first member 10 relative to fourth member 18 until cutting stylus 52 is exactly over the end of the last recorded groove on the recording disc. Set screws 26 and set screws 44 and 46 are then tightened, permitting a light pressure on cutter head 42 by spring 56.

With cutting stylusSZ still out of contact with the recording disc, the turntable is rotated and second member 14 is held by handle 16, running cam follower 58 through one complete cycle of eccentric groove 12 to check'for interference with cutting stylus 52. Turntable isnow rotated to return cam follower 53 to its starting point. Advance ball 54 is raised by adjusting screw 43, permitting-cutting stylus 52 to engage the end of the last'recorded groove of the recording disc. Handle 16 isgrasped firmly, and the turntable is rotated clockwise, cutting the required eccentric groove in the recording disc.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings, It is thereforeto be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

We claim: I

l. A'device for cutting a terminating eccentric groove on a recording-disc, said device comprising a first member having a flat face, an eccentric groove cut into said face toform 'a cam disposed-about a given point which iscentrally located with respect to said cam, said eccentric grove cutinto said face havingthe same configuration as the eccentric groove to be cut in said recording disc; a second member rotatable relative to said first member about a line passing through said point perpendicular to said face, said second member extending above said face; a longitudinal third member passing through said second member and axially slidably engaged therewith, said third member being located above said face with the longitudinal axis thereof parallel to said face and intersecting said line; a cam follower connected to said third member and extending parallel to said line and riding in the grove of said cam, and a cutting head connected to said third member a given distance beyond said cam follower relative to the position of said line; wherein said first member comprises a right circular cylinder having said line as the axis thereof and said face being one transverse surface thereof, said cylinder having a portion thereof cut away, said cut away portion being circular about the axis of said cylinder and extending in an axial direction from the other transverse surface of said cylinder to a point below said face; said device further comprising a fourth memberfitting into the cutaway portion of said cylinder, said fourth member being rotatable relative to said cylinder, and means for locking said fourth member to said cylinder to prevent relative rotation therebetween.

2. The device defined in claim 1 wherein said locking means comprises a hole through said fourth member perpendicular to said axis, a circular groove in said cylinder in cooperative relationship with said hole, a slug fitting into said hole and circular groove, and a set screw for exerting pressure on said slug against the bottom :of said circular groove.

3. The'device defined in claim 2, wherein said cylinder has a hole therethrough coaxial therewith, and wherein said second member fits into said hole and is rotatable relative to said cylinder. I

4. The device defined in claim 3, wherein the bottom of said second and fourth members lie in a plane perpendicular to said axis, and-wherein the bottom of said second member has a first indentation therein symmetrical with saidaxis, said first indentation being-engageable with the center pin of a standard recording turntable, and said fourth member having a second'indentation therein, said second indentation being engageable with the drive pin of a standard recording turntable.

5. The device defined in claim 4, further comprising means for adjusting said given distance;'

6. The device defined in claim 5, wherein said means for adjusting said given distance comprise first and second movable collars slidably disposed on said third member, one of said collars being located on one side of said cutting head and the other of said collars'being located on the other side of said cutting head, each of said collars being equipped with a set screw for secur ing that collar to said third member, and a spring disposed between one of said collars and said cutting head.

7. A device for cutting a terminating eccentric groove on a recording disc, said device comprising a first member having a flat face, an eccentric groove cut into said face to form a cam disposed about a given point which is centrally located with respect to said cam, said eccentric groove cut into said face having the same configuration as the eccentric groove to be cut in said recording disc; a second member rotatable relative to said first member about aline passing through said point perpendicular to said face, said second member extending above said face; a longitudinal third member passing through said second member and axially slidably engaged therewith, said third member being located above said face with the longitudinal axis thereof parallel to said face and intersecting said line; a cam follower connected to said third member and extending parallel to said line and riding in the groove of said cam, a cutting head connected to said third-member a given distance beyond said cam follower relative to the position of said line, and means for adjusting said given distance including first and second'movable collars slidably disposed on said third member, one of said collars being located on one side of said cutting head and the other of said collars being located on the other side of said cutting head, each of said collars being equipped with means for securing that collar to said third member, and a spring disposed between one of said collars and said cutting head.

References Cited in thefile of this patent UNITED STATES PATENTS 552,293 Kuhn Dec. 31, 1895 742,047 Moehle Oct. 20, 1903 2,493,511 Van Eps Jan, 3,- 1950 2,595,795 Kovach May 6, 1952 

